1. Field of the Invention
The present invention relates to an aircraft motor drive control apparatus and an aircraft motor drive control system that drive a motor mounted to an aircraft for driving a device installed in the aircraft and that control the operational status of the motor.
2. Description of Related Art
Various electrically powered devices are installed in an aircraft, and such devices are driven by motors (electric motors) mounted to the aircraft. Examples of the aforementioned devices include an electrically powered hydraulic pump for supplying pressure oil to a hydraulically operated actuator for driving control surfaces that are formed as moving surfaces (flight control surfaces) and are configured, for example, as an aileron and an elevator, as disclosed in JP 2007-46790A. Other examples include an electric actuator for driving the above-described control surfaces and a leg (a mechanism supporting the body of an aircraft on the ground) such as a landing gear (undercarriage).
A motor drive control apparatus (aircraft motor drive control apparatus) that is also mounted to the aircraft controls a motor for driving the above-described devices, and controls the operational status of the motor. From the viewpoint of increasing the efficiency, it is possible to use, as such a motor drive control apparatus, a motor drive control apparatus including an inverter that includes a switching element and that drives a motor and a control part that performs a pulse width modulation control (PWM control) of this inverter.
For the above-described motor drive control apparatus including an inverter and a control part that performs PWM control, the control performance can be improved by increasing the PWM frequency, which is the switching frequency (carrier frequency) of the switching element. However, an increase in the PWM frequency leads to an increase in the loss of the switching element that is proportional to the PWM frequency, resulting in an increase in the amount of heat generation as well. Therefore, it is desired to provide a motor drive control apparatus that can ensure control performance and suppress heat generation in a well-balanced manner.
On the other hand, JP 2010-57243A discloses, as a motor drive control apparatus provided in a vehicle, a motor drive control apparatus that controls the PWM frequency from the viewpoint of reducing the noise generated depending on the frequency band of the PWM frequency, in addition to the viewpoints of ensuring control performance and suppressing heat generation. Note that the motor drive control apparatus disclosed in JP 2010-57243A is configured to perform a synchronous PWM control if the current supplied to the motor by an inverter or the torque generated in the motor is greater than a threshold. Also, the motor drive control apparatus is configured to perform a synchronous PWM control or an asynchronous PWM control and to set the PWM frequency higher than in the case where the above-described current or torque is greater than the threshold if the above-described current or torque is smaller than the threshold.